The study represents the most comprehensive assessment of freshwater biodiversity across an entire continent. It combined the range maps for 4,203 freshwater species and 3,521 terrestrial species across Africa with data on IUCN Red List extinction risk, protected area coverage, large dam presence and rural poverty to analyse the status, threats and protection for freshwater biodiversity.

Terrestrial species act as poor surrogates for freshwater species

Darwall and colleagues found that terrestrial and charismatic species are poor surrogates for capturing the distribution and threat towards many freshwater species. As the authors state: “for fish, molluscs and crabs, results suggest that conservation priorities and investment targets based on our knowledge of birds, mammals and amphibians alone may not adequately represent these freshwater species”.

The authors argue that conservation research biased towards terrestrial and charismatic species means that our knowledge of global freshwater biodiversity patterns and trends is fragmented and incomplete. Because protected areas for biodiversity conservation are often planned using ‘surrogate’ species – where the protection of well-known and documented taxa is thought to act as ‘umbrella protection’ for those less well-known – freshwater ecosystems are currently under-protected from a myriad of human and climate based threats.

Fisherman on Lake Tanganyika. The number of known threatened species in the African Great Lakes increased based on the findings of this study. Image: Wikipedia

Conservation and ecosystem service needs not met by existing protected areas

The dynamic, trans-boundary nature of freshwater ecosystems mean that their conservation needs are often not met by protected areas planned around terrestrial ecosystems. The bias towards research on terrestrial biodiversity means that often freshwater systems are not congruent with existing protected areas.

Importantly, the study found that in Africa, areas of highest freshwater species richness and threat overlap significantly with areas where reliance on ecosystem services by humans is high. In addition, these areas are commonly under high pressures from humans. In this study, of the 4,203 freshwater species assessed, 26% were found to be threatened with global extinction. However, shortfalls in our knowledge of freshwater biodiversity meant there was insufficient information to assess the status of 741 freshwater species in the study, meaning the extinction threat level could be as high as 37%.

The River Nile in Cairo. Image: Wikipedia

Threats to freshwater ecosystems and human livelihoods

Why is this study important? Freshwaters represent one of the most threatened ecosystems globally – they contain over a third of the world’s known species and around a third of all vertebrates despite occupying less than 1% of the Earth’s surface. Human population growth and economic development threaten the health and integrity of many global freshwater ecosystems, compromising their ability to support biodiversity and provide ecosystem services such as irrigation, sanitation and food supply to humans.

The urgent need for targeted freshwater biodiversity research and funding

The key conclusion of the article is that there is a strong case for a shift in research and targeted investment towards freshwater biodiversity to reflect the value and importance of freshwater ecosystems and the services they provide. Better-known (often terrestrial) taxonomic groups do not act as adequate surrogates for freshwater species when planning conservation management. Improved data on freshwater species is needed to underpin the expansion of the existing network of protected areas to adequately protect threatened freshwater systems.

What is The Freshwater Blog?

Features, interviews and analyses on freshwater conservation, science and policy.

For comments, ideas and submissions, you can contact us here: info [at] freshwaterblog.eu

The blog was founded and edited between 2010-14 by the BioFresh project, an EU-funded project that built a global information platform for scientists and ecosystem managers with access to all available data describing the distribution, status and trends of global freshwater biodiversity.

Since 2014, the blog has been managed and edited by the MARS project – an EU-funded project which investigates how multiple stressors affect rivers, lakes and estuaries.

The Freshwater Information Platform provides up-to-date information on freshwater science as well as an array of research resources and tools for the assessment and management of freshwater ecosystems.